Atomic-scale insights into Electrocatalyst Structure and Function

Shoji Hall - Johns Hopkins University

The development of efficient renewable energy conversion and storage devices is one of the most important challenges of the 21st century. Fuel cell catalysis, CO2 reduction, etc. are promising reactions for transforming our energy economy. However, these reactions are sluggish because of unfavorable reaction kinetics and suffer from poor product selectivity. Ordered intermetallic compounds (OIC) can exhibit enhanced performance and selectivity for mediating electrochemical reactions relative to solid-solution alloys. However, OICs often require high temperature and pressure to synthesize, resulting in poor control of the morphology and phase-purity. Despite decades of intense research, OICs nanoparticles have failed to replace conventional solid solution nanomaterials because of a lack of low-temperature synthetic methods that can overcome slow solid-state diffusion rates, and the inability to tune composition and phase while maintaining morphology. In this talk I will discuss our efforts on the synthesis, stability, and catalytic activity of OICs prepared by electrochemical methods at room temperature and atmospheric pressure. Our strategies include the use of electrochemically induced phase transformations which enables us to convert a base metal rich alloy to an OIC richer in nobler metal by removal of the base metal, and the direct production of OIC materials by electrochemical deposition. Developing new methods for preparing OIC compounds under ambient conditions is essential for designing catalysts for the next generation of renewable energy conversion devices.